Update oauth2 code for 2026.03 release

[jwillemsen]

https://developers.home-assistant.io/blog/2026/02/19/oauth-token-request-error-handling/

[Saubin38]

Hi,
Is it the reason why i can get entities unavailable after upgrading and sign in again into onecta cloud ?

[jwillemsen]

No, that should be something else, this is just some error handling

[Saubin38]

Ok thx. Do you know the good way to delete the token ? I try with the web UI and it says I can't delete the cred when it's used. I try with the extension disable.